Note: Descriptions are shown in the official language in which they were submitted.
WO 95/32372 218 9 6 7 8 pCTlCA95100299
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DYNAMIC BALANCING METHOD ANP APPARATUS
INTRODUCTION
This invention relates to a balancing method
and apparatus and, more particularly, to a balancing
method and apparatus used for dynamically balancing an
out of balance condition in a rotating body.
BACKGROUND OF THE INVENTION
Many different apparatuses for balancing an
out of balance condition in a rotating body are known.
Such apparatuses generally include a counterweight
having a weight of a predetermined value which is
located at a predetermined position from the axis of
rotation to oppose an imbalance in the rotating body.
The magnitude of the imbalance is generally known and,
accordingly, the necessary weight and position of the
counterweight can be calculated so that the weight is
positioned where it will act to counter the known
imbalance. These apparatuses function satisfactorily
for most purposes under which they are employed but are
not precise or useful enough for other applications.
Under dynamic conditions; that is, when a
body is rotating about an axis and an imbalance in the
rotating body develops because of external conditions
or otherwise, the prior art is much less satisfactorily
developed. For example, in a drill bit or in a
drillstring, vibration induced forces during operation
can create severe imbalances. One technique used to
counteract such imbalances is disclosed in V.S. Patent
4,905,776 (Beynet et al). Beynet et al teach a
vibration dampening assembly cvith a plurality of
annular grooves or races located about the periphery of
WO 95/32372 PCT/CA95/00299
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ky
the assembly and extending axially therealong. A
plurality of balls or rollers are located in each of
the races. Such balls or rollers are free to move
along the races and thereby counteract the imbalance
forces.
A further similar structure is disclosed in
U.S. Patent 4,674,356 (Kilgore). ICilgore teaches a
plurality of balls freely movable in a race formed in
an outer circumferential surface of the body which
balls are used to counterbalance an imbalance in the
rotating member.
There are, however, disadvantages in such
prior art. Although the Beynet et al reference is
satisfactory to remove large imbalances from the
rotating body, it is difficult to utilise the teachings
of Beynet et al where the length of the balancing
apparatus is necessarily restricted which is often the
case. Likewise, while the teachings of Beynet et al
are satisfactory to generally remove large imbalances
from the drillstring, there is no provision therein for
removing all or most of the remaining imbalance
thereafter, particularly the imbalance that may remain
when the balls in the races of Beynet et al are located
at their optimum positions in the races to counteract
the imbalance.
This latter problem is also inherent in the
above mentioned Kilgore reference. Kilgore teaches two
counterbalance structures, one located at each end of a
shaft, to offset the imbalance in the shaft or the
imbalanced forces in the rotating structure which is
movable with the shaft. If the balls are not located
at their optimum positions, the imbalance in the shaft
will not be removed.
WO 95/32372 489lj ~+ ry n PCTlCA95l00299
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The dynamics of weight movement in the
various races of the balancing apparatus is an
important consideration for efficient movement of the
weights in order for the weights to properly "set up"
and remove imbalances under various operating
conditions. Such conditions may include the
acceleration of a rotating apparatus from zero to some
predetermined steady-state operating speed or
revolutions (r.p.m.'s), the operation of a machine
between two natural modes of vibration which are
inherent in a particular system and the operation of a
machine or apparatus that is subjected to additional
non-one time per revolution excitations; that is,
forces which are applied to the apparatus with
frequencies different from the rotational speed of the
apparatus.
In a single race with movable weights, many
of the weights in the race tend to respond to the
varying operating conditions in a similar general
fashion in view of the similar masses and sizes of the
movable weights. In addition, the weights will often
contact each other and interference with the
independent movement of the individual weights results.
This can lead to a case wherein an imbalance condition
is not removed or substantially removed. However, with
more than one race, each race having a plurality of
weights, the movement of the weights in each race is
independent from the weights of the other race and,
accordingly, each plurality of weights responds to
varying operating conditions in a different manner.
This is beneficial because if the movable weights in
the first race respond inappropriately to remove an
imbalance, such as drifting away from their optimal
desired position, the movable weights in the second
race may respond appropriately and may also tend to
WO 95/32372 PCT/CA95/00299
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.:~
influeace, compensate for,=,preiminate the
inappropriate behaviour of the movable weights in the
first race. These phenomena in two race and greater
apparatuses are referred to as "race for race"
compensation.
The independent movement of the weights at
different times is under the influence of several
variables. Some such variables include the material of
the weights and races, the configuration of the weights
and races, the size of the weights and races, the
diameter of the various races and the presence or
absence of fluids in the various races. If there are
fluids present, then the viscosities of the fluids used
are of particular importance.
The independence of the movement of movable
masses can be established by varying the dynamics of
the individual races. The dynamics of the weight or
ball movement in a manner different than having balls
of different sizes in different grooves is of
importance. it has been found that, with other factors
being equal, balls made from a denser material will
respond faster to imbalance than lighter balls. This
faster response of the weights or balls may be
implemented by manufacturing the movable weights from a
material such as carbide material, which is denser than
the density of known steel material. It is also noted
that earlier movement of the balls can result if the
weights are made of hard material and are therefore
able to move more freely. Likewise, it is noted that
earlier movement of the weights or balls can be
achieved if the races in which the weights move are of
a relatively hard material.
WO 95/32372 21aJU~ n e78 PCT/CA95/00299
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A further parameter affecting the movement of
the weights within the races is the presence or absence
of fluid and the viscosity of such fluid. More
particularly and with other factors being equal, the
use of a fluid with a greater viscosity will delay the
movement of the balls or weights in the race while the
presence of a fluid having a lesser viscosity will
allow the movement of the weights to take place more
readily. Thus, if there are a plurality of races, the
use of different fluids in different races will allow
the movement of the weights in each race to take place
at a predetermined rate which may be useful in certain
applications.
For example and, again, other factors being
equal, if there are two races with the same size
weights in each race, the use of a fluid with a first
viscosity in the first race and a fluid with a second
viscosity in a second race, the viscosities of the two
fluids being different, the weights in the second race
with the fluid of the second race having a higher
viscosity will, upon startup, move and "set-up" earlier
to remove the imbalance than the balls or weights in
the first race. Conversely, the higher viscosity fluid
will tend to delay the movement of the weights or balls
at operating speeds when the balls are already "set-up"
to remove an initial imbalance and a further imbalance
appears in the apparatus. Thus, depending on the
operating characteristics desired, a fluid of a first
viscosity can be used to enhance "set-up" at low speeds
and a fluid of a second viscosity can be used to
enhance "set-up" at higher speeds. In this ma*+++er, it
is possible to design a system which will set up to
remove the imbalance at a predetermined time,
predetermined speed of angular rotation, or
predetermined angular acceleration of the member. And,
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while a system using two races has been described, it
is contemplated than different fluids could be used in
each race of a balancing apparatus, wherein the
apparatus has three or more races.
it is again emphasized that the explanations
given herein are believed to be correct based on
empirical and calculated results and laboratory
simulations. However, subsequent investigations may
well reveal that these explanations will be modified
and such explanations are given here for the purpose of
full disclosure of the technology which is sought to be
protected.
$UhO7IiRY OF TFIE INVEWTION
According to one aspect of the invention,
there is provided an apparatus to remove an imbalance
in a rotating member comprising first, second and third
pathways formed concentrically about the axis of
rotation of said rotating member, first, second and
third movable weights guided by each of said first,
second and third pathways, respectively, the size of
said weights in each of said first, second and third
pathways being substantially identical.
According to a further aspect of the
invention, there is provided an apparatus to remove an
imbalance from a rotating member having an axis of
rotation comprising a guide member located
circumferentially around said member and a plurality of
weights being guided by said guide member and being
freely movable thereon.
According to yet a further aspect of the
invention, there is provided an apparatus to remove an
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imbalance from a member rotating about an axis
comprising a first pathway having a width and being
positioned concentric to the said axis, said pathway
having a circumference at a first distance from said
axis and a second pathway located at a second distance
from said axis and being axially displaced from said
first pathway, said second distance being greater than
said first distance and movable weights positioned in
each of said first and second pathways.
According to yet a further aspect of the
invention, there is provided a balancing apparatus to
remove imbalance in a rotating body comprising a first
plurality of weights movable within a first circular
race, a second plurality of weights movable within a
second circular race, said first circular race further
including a first fluid with a first viscosity, said
second circular race further including a second fluid
with a second viscosity, said viscosity of said second
fluid being different from said viscosity of said first
fluid.
According to yet a further aspect of the
invention, there is provided a balancing apparatus
comprising a first circular race rotatable about a
first axis, a first plurality of weights movable within
said first race, a locking member operable to maintain
said first plurality of weights in a first position
reached at a first predetermined angular velocity and
to release said first plurality of weights from said
first position at a second predetermined angular
velocity.
According to yet a further aspect of the
invention there is provided a method of removing the
imbalance from a rotating apparatus comprising
WO95/32372 PCT/CA95/00299
2189678"
-8
increasing the rotation speed of said apparatus until a
first predetermined rotation speed is reached,
maintaining a plurality of movable weights in a first
race in a first position of said weights which is
reached at a first predetermined rotation speed,
increasing said rotation speed of said apparatus to a
second predetermined rotation speed and releasing said
plurality of movable weights from said maintained
position at said second predetermined rotation speed.
Rccording to yet a further aspect of the
invention, there is provided a balancing apparatus to
removed imbalance in a rotating body comprising a first
plurality of weights in a first race, said first race
having a first configuration and a second plurality of
weights in a second race, said second race having a
second configuration, said configuration of said first
race being different from said configuration of said
second race.
BRIEF PESGRIPTION OF TEiE SEVERAL VIEWS OF TFiE DRAWINGS
Specific embodiments of the invention will
now be described, by way of example only, with the use
of drawings in which:
Figure 1 is a side sectional diagrammatic
view of a first embodiment of the counterbalancing
apparatus according to the invention;
Figure 2 is an end view taken along II-II of
Figure 1;
Figure 3 is a side sectional diagrammatic
view of a second embodiment of the counterbalancing
apparatus according to the invention;
WO 95/32372 ~~ g g~ 7 g PCTlCA95I00299
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Figure 4 is an end view taken along IV-IV of
Figure 3;
Figure 5 is side sectional view of a further
embodiment of the counterbalancing apparatus according
to the invention;
Figure 6 is g side sectional diagrammatic
view of a further embodiment of the counterbalancing
apparatus according to the invention;
Figure 7 is a side sectional diagrammatic
view of the apparatus of Figure 6 illustrated in its
operating position;
Figures 8A and 8B are end views of a further
embodiment of the invention mounted about a shaft and
illustrating the counterbalancing apparatus in
assembled and disassembled condition about the shaft,
respectively;
Figure 9 is a diagrammatic aide view of yet a
further embodiment, the counterbalancing apparatus
according to the invention being operably located
within a shaft;
Figure 10 is a diagrammatic end view taken
along X-X of Figure 9 illustrating a representative
position of the movable weights during rotation of the
shaft in which the apparatus is located;
Figure 11 is a view of the counterbalancing
apparatus according to the invention illustrating the
vertical radial from the axis of the apparatus;
WO 95132372 PCT/CA95/00299 ~4"~
2189678
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Figure 12 is a diagrammatic cross-sectional
view of a ball retaining apparatus according to a
further embodiment of the invention;
Figure 13 is a diagrammatic cross-sectional
view of a ball retaining pin apparatus according to a
further embodiment of the invention;
Figure 14 is a cross-sectional view of two
versions of balancing devices according to the
invention, either of which might be used with an
ordinary ball bearings;
Figure 15A is a diagrammatic view of the
outside of the tub of a washing machine with balancing
devices mounted thereon;
Figure 15B is a diagrammatic view taken along
i5B-15B of Figure 15A;
Figure 15C is a diagrammatic view taken along
15C-15C of Figure 15A;
Figure 16 is a diagrammatic view of the rear
end drive axle and differential of a vehicle;
Figure 17 is a view of a typical crankshaft
which is connected to a piston of a compressor or
internal combustion engine with balancing devices
attached according to the invention;
Figure 18 is a side-sectional diagrammatic
view of yet a further embodiment of the invention;
WO 95/32372 218 A(~ q~ PCT1CA95100299
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Figures 19A and 19B illustrate a
circumferential I-beam arrangement according to a
further aspect of the invention; and
Figure 20 illustrates a mounting arrangement
according to a further aspect of the invention.
Figure 21 is;a diagrammatic isometric view of
a weight locking apparatus according to a further
aspect of the invention which is used to restrain the
weights over a predetermined range of speeds;
Figure 22 is a side, diagraa~natic cutaway
view of a balancing device according to the invention
in which the movable weights are first held in position
until a predetermined speed of rotation is reached
whereupon release then occurs;
Figure 23 is a diagrammatic cutaway view of a
balancing device according to the invention which
utilizes a plurality of free weights and a further set
of weights released by control weights; and
Figure 24 is a diagrammatic cutaway view of
two representative race configurations which will
modify the behaviour of the weights during operation
according to a further aspect of the invention.
DESCRIPTION OF SPECIFIC EkSEODIMENT
Referring now to the drawings, a
counterbalancing apparatus according to the invention
is illustrated generally at 10 in Figure 3. It
comprises a first set of annular races or grooves 11,
12, 13, 14, 15, it being understood that oppositely
located races 11, 15 are conveniently identical and
WCt 95/32372 21 Q Q C~1 Q PCT/CA95/00299
2189678
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that oppositely located ra~es 12, 14 are also
conveniently identical. It will be understood that the
term "race" or "races" refers to the physical boundary
within which the weights move during operation or,
alternatively, it could also include a pathway which
acts to guide weights movable thereon or therein as
described in greater detail below.
A plurality of weights 21, 22, 23, 24, 25,
conveniently spherical in the form of balls, are
mounted in the races 11, 12, 13, 14, 15, respectively.
The plurality of weights in each of the races are
conveniently all the same size and weight; that is, the
weights 21 in race 11 are all the same size and weight,
the weights 22 in race 12 are all the same size and
weight and so on. It is important, however, that the
weights in at least two of the races be different in
size and weight; that is, the weights 23 in race 13 are
preferably larger and heavier than the weights 24 in
race 14. It will be further understood that the term
"weights" may include a variety of different shapes
such as spherical, disc or cylindrically shaped weights
which are movable within the races or guided thereby.
The term may also include weights of different
configuration as is described further in this
specification.
The balls 21, 22, 23, 24, 25 are freely
movable in their respective races 11, 12, 13, 14, 15
about the circumference of the counterbalancing
apparatus 10. An appropriate lubricant 30,
conveniently silicon, is added to the counterbalancing
apparatus 10 in order to reduce the friction between
the balls and their respective races or grooves, to
also reduce the noise made by the balls when the
counterbalancing apparatus is in operation, and to
WO 95/32372 2189 6 78 PCTICA95100299
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create an appropriate amount of viscous dampening to
the balls as will be described hereafter.
The balls 21, 22, 23, 24, 25 may be
man.ufactured from a hardened material. Likewise, the
races or grooves 11, 12, 13, 14, 15 may be hardened.
The hardening is desirable in order to prevent the
formation of "flats" on the balls or races which tend
to reduce the ability of the balls to move freely
within the grooves or races and thereby retard the
effectiveness of the counterbalancing movement of the
balls.
OPERATION
In operation, the counterbalancing apparatus
10 is installed on shaft 32 so as to fixedly rotate
therewith such as by using a key 31 between the
apparatus 10 and the shaft 32. The operation of an
imbalanced member generally illustrated at 33, which
creates an out of balance condition, is initiated and
shaft 32 rotates with member 33 and counterbalancing
apparatus 10 as illustrated.
As an out of balance condition originates
within member 33, the balls 21, 22, 23, 24, 25 in each
of the races 11, 12, 13, 14, 15 move and act to
counterbalance the out of balance condition.
It is difficult to precisely state all the
principles by which the balls are known to move and
while it is believed that empirical data will
subsequently lead to formulae and better understanding
to predict the optimal behaviour of the
counterbalancing apparatus 10, the following
explanation is given with the expectation that further
WO 95/32372 21$ 9 6( Q PCT/CA95/00299 .
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information presently not known will amplify, modify or
change such explanation.
it is believed that the larger balls 23 in
race 13 will remove the larger out of balance condition
in member 33. The somewhat smaller balls 22, 24 in
races 12, 14 will act to remove the somewhat smaller
out of balance condition in member 33. Finally, the
smallest balls 21, 25 in races 11, 15 will act to
remove the amallest out of balance condition in member
33. Thus, the entire out of balance condition in
member 33 is removed by "fine tuning"; that is, by
removing the imbalance under dynamic conditions with a
plurality of different sized_balls positioned in
separate races which balls optimally remove different
degrees of imbalance.
With reference to Figure 4 which illustrates
the leftmost race 11 of Figure 3 with the balls 21 in a
representative and dynamic balanced position offsetting
the imbalance in member 33, as viewed with a timing
light adjusted for appropriate shaft r.p.m., it has
been found that the optimum behaviour for the balls 21
occurs when they do not contact each other in the
dynamically balanced position as is illustrated. It
has been found that when many of the balls 21 come into
contact with each other, the balancing phenomenon is
not optimal and modification of the counterbalancing
apparatus 10 may be necessary by way of structural or
weight changes.
The embodiment of the invention illustrated
in Figures 3 and 4 is conveniently used when there is a
large potential imbalance problem in member 33 under
dynamic operating conditions. If the potential
imbalance problem in member 33 is sma11, the number of
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races and associated balls therein can be reduced to as
few as two (2), with all of the balls in each
respective race being the same size and weight and the
balls of the first race being different in size and
weight from the balls of the second race, the former
balls being larger and acting to remove the large
imbalance and the latter balls being smaller and acting
to remove the smaller remaining imbalance.
Referring now to Figures 1 and 2, there is
illustrated a further embodiment which is desirably
used when the width "W" as illustrated in Figure 1 is
limited. in this embodiment, there are three grooves
or races 34, 35, 36 with balls 40, 41, 42 mounted
therein, respectively. The balls 40 in race 34 are all
the same size and weight. The balls 41 in race 35 are
likewise all the same size and weight and the balls 42
in race 36 are likewise all the same size and weight.
The balls 40 in race 34, however, are larger and
heavier than the balls 41 in race 35 which, in turn,
are larger and heavier than the balls 42 in race 36.
Under operating conditions and when an imbalance occurs
in member 33 during rotation of shaft 32, the balls 40,
41, 42 will assume positions which counter the
imbalance. A representative view of the positions of
balls 40, 41, 42 illustrated in Figure 2 would be
positions where the imbalance is removed optimally;
that is, and as earlier described, the balls in each
race or groove do not contact each other.
A further embodiment of the invention is
illustrated in Figure S. In this embodiment, wherein
the width "W" is again of concern, a first plurality of
cylindrical disc-like weights 50, 51, 52 are positioned
to be freely movable in each of the races 43, 44, 45
which races 43, 44, 45 are formed by circumferential
.t.
PCT/CA95/00299
WO 95132372 2~ 896 78.
Cb
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dividers 53, 54, 55 which are positioned over hub 60
and between spacers 61, 62, 63. A silicon lubricant 65
is added to the interior of the housing 64 and a
closure member 70 is connected to the housing 64 by the
use of cap screws 71.
In operation, the housing 64 is fixedly
mounted on the rotating shaft 32 as described in
association with the method of Figure 1. As an
imbalance arises in member 33, the cylindrical weights
50, 51, 52 will freely move within the races 43, 44, 45
until they assume a position wherein they
counterbalance the imbalance occurring in the member
33. It has been found that it is preferable to give
the sides of the cylindrical disks 50, 51, 52 a slight
bow in order that the discs 50, 51, 52 contact the
dividers 53, 54, 55 with a minimal surface area wherein
they are not influenced by any possible suction which
might otherwise occur between the dividers 53, 54, 55,
the silicon lubricant 65 used and the discs 50, 51, 52
of the Figure 5 embodiment. It is preferable that the
cylinders or discs 50, 51, 52 move as freely as
possible within the races 43, 44, 45 between the
dividers 53, 54, 55 as is likewise true for the weights
and balls of the Figures I and 3 embodiments.
Yet a further embodiment of the invention is
illustrated in Figures 6 and 7, Figure 6 illustrating
four (4) grooves or races and Figure 7 illustrating
only three (3) grooves or races. In this embodiment,
the counterbalancing apparatus generally illustrated at
75 is symmetrical about both axes 76, 72 and is mounted
to a shaft 32 similar to the Figure 1 embodiment.
in this embodiment, however, a central
circumferential member 73 made from a solid piece of
WO 95/32372 2~ 8967V PCTlCA95100299
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material is machined with a plurality of anaular races
generally illustrated at 77 on both faces. Balls are
mounted in the races 80, 81, 82, 83, the balls mounted
in the outermost race 80 being the largest and the
balls in the innermost race 83 being the smallest.
After providing the silicon lubricant within each of
the races 77, two end plates 85 are mounted to the
central circumferential member 73 by the use of cap
screws 82. The operation is similar to the operation
of the Figure 3 embodiment; that is, when an imbalance
occurs in member 33, the balls in each race will assume
a position wherein the imbalance is removed.
It is not again presently known why such is
the case, but it has been found that seven (7) balls or
weights in each race or annular space of each of the
embodiments appear to be an optimal number. It is,
however, also believed that a greater or emaller number
of balls or weights would usefully serve to remove
various imbalances under various operating conditions.
A further embodiment of the invention is
illustrated in Figures 8A and 8B. In this embodiment,
the counterbalancing apparatus 78 according to the
invention is illustrated as being made from two
sections 90, 91, which sections are mounted about shaft
32 by cap screws 92, 93 and which sections 90, 91 are
freely removed from shaft 32 by removing the cap screws
92, 93. This embodiment is particularly useful where
minimal modifications are desirably made to the
rotating shaft 32 or to the out of balance member 33
(Figure 1). Rather, the counterbalancing apparatus 78
is simply connected to the shaft 32 at a position where
it is possible so to attach the counterbalancing
apparatus 78 and the cap screws 92, 93 are tightened to
firmly couple the apparatus 78 to the shaft 32.
WO 95/32372 PCTlCA95/00299
2189678
Yet a further embodiment is illustrated in
Figures 9 and 10. In this embodiment, it is
contemplated that the counterbalancing apparatus 87 is
mounted inside the outer circumference of a rotating
shaft 32. As illustrated in Figure 9, the grooves or
races 100, 101, 102 are machined directly into the
solid material of shaft 32 and the balls 103, 104, 105
are positioned directly therein for free movement
relative thereto. A cover 110 is connected to the
shaft 32 and the balls 103, 104, 105 are thereby
retained. In operation, as an out of balance condition
occurs either in the out of balance member 33 (Figure
1) or in shaft 32 itself, the balls 103, 104, 105 will
orient themselves in a configuration such as the
configuration illustrated in Figure 10. In such
positions, the shaft 32 and/or the imbalanced member 33
is balanced by the position of the balls 103, 104, 105
under dynamic operation conditions.
It has been found that under certain
conditions and particularly at lower r.p.m.'s of the
counterbalancing apparatus 10, the weights 21 (Figure
11) will tend to remain in a substantially stationary
position in the race 11 until the revolutions per
minute of the counterbalancing apparatus increase to
the point where the weight 21 is carried around the
outermost point of the inside diameter of the race 11
or from one side of the radial 25 to the other or until
the centrifugal force acting on the weights forces them
outwardly until they are in an operating engagement
with the outer surface of the race 11 which will then
exert a certain friction force that will tend to carry
them around with the race 11. After operating speed
occurs, the weights 21 will then quickly rearrange
themselves with minimal movement so as to properly
balance any imbalance condition. It has been found,
WO 95132372 Z1 Q/t ~ Aj~ PCTICA95100299
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for example, that at higher rotational speeds of the
balancing device, the weights 21 within the races will
quickly rearrange themselves to set off any imbalance
in the device. However, at lower speeds, this not
always the case and, accordingly, it is convenient to
utilise means to move the weights with the race or, at
least, to provide a force on the movable weights which
will tend to move the weight with the race as it
rotates about its axis.
Any delay in removing the imbalance is not
advantageous since if a shaft, for example, being in
balance and rotating, suddenly encounters an out-of-
balance condition, it is conceivable that the weights
21 may not move quickly enough to remove the out-of-
balance condition before damage results to the system.
The means used to improve the "quickness"
with which the system responds to remove the out-of-
balance condition can take several forms. It is, for
example, contemplated that a substance could be added
to the races 11 so that a force is imparted to the
weights 21 which force will be such that the weights 21
will move from a stationary position as indicated to a
position "over-the-top" of the member 10 and from one
side of the radial 25 extending from the axis 26 of the
member 10 to the opposite side. Alternatively,
mechanical or electrical means could be used.
With reference to Figure 11, it is
contemplated that the initial movement of the weights
21 within the race 11 may occur by the addition of a
substance to the races 11 that will initially give a
degree of force to the weight so that the movement of
the weights 21 is initiated by the substance. For
example, such a substance could be a fluid of a
WO 95/32372 PCT/CA95/00299
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consistency to impart the rotational movement to the
weights, such as grease. An exhaustive list of all
such substances is not immediately contemplated but
such a list might include virtually any substance to
initiate movement of the weights 21. Even sand is
contemplated as such a substance but, of course, sand
may be inappropriate because of contamination and
eventual binding of the weights 21 within the race 11
which would affect normal operation where quickness of
weight movement may not be necessary.
It is also contemplated that the initial
weight movement could be initiated externally of the
counterbalancing apparatus 10. For example, if the
weights 21 were made of a magnetic material, an
external probe (not illustrated) could apply a suitable
magnetic field to the weights 21 which would allow the
weights 21 to immediately commence movement in the
event an imbalanced condition is encountered. This
would be intended to reduce the rotation time of the
weights 21 so that the imbalanced condition can be
removed and would thereby reduce the chance of damage
to the out-of-balance apparatus.
Reference is made to Figure 12 which
illustrates the balancing device generally illustrated
at 106. A liquid 107 is added to the balancing device
106 and takes a level 108 above the movable weight in
the form of ball 103. A V-shaped race 109 is formed in
race 110 in which ball 103 is intended to move. The V-
shaped race 109 has a plurality of passages 111 which
extend from the race 109 to a liquid reservoir (not
illustrated).
in operation and when the balancing device
106 begins to rotate, the liquid 107 will tend to
~ WO 95/32372 ~'rq 189678 PCTlCA95100299
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rotate with the race 110 and, therefore, will exert a
force on ball 103 which tend to rotate the ball 103
with the race 110. As the speed of rotation of the
balancing device increases, the centrifugal force on
0 5 the liquid will increase and, therefore, there will be
a tendency for the liquid 107 to exit through
passageway 111 and thereby to terminate any further
influence over the movement of ball 103 which, by that
time, will be rotating at the same speed as the
balancing device 106. This is beneficial for the
previously mentioned reasons, namely that if the balls
103 move quickly at speed, any imbalance arising will
be quickly corrected.
A further embodiment of the invention is made
with reference to Figure 13. The balancing device
generally illustrated at 200 includes a movable weight
in the form of a ball 201 and includes a pin 202 which
is spring mounted within a radially outwardly extending
opening 204. A compression spring 203 acts on the pin
202 to force it inwardly to the position indicated and
thereby restrains movement of the ball 201 upon initial
rotation of the balancing device about axis 206.
As the balancing device 200 commences to
rotate about axis 206, the pin 202, in the position
illustrated, will cause the ball 201 to rotate with the
race 205. The speed will increase and as it does so,
the centrifugal force acting on the pin 202 will tend
to move the pin 202 outwardly from axis 206 in opening
204 thereby allowing the ball 201 to move in the race
205 thereby to freely assume any position to correct an
imbalance in the rotating machinery to which the
balancing device 200 is attached.
WO 95/32372 PCTICA95/00299
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Reference is now made to Figure 14 which
diagrammatically illustrates two embodiments of the
invention which may be used with a bearing 300 having
standard balls 301 mounted so as to allow rotation of
shaft 302 with reduced friction. However, it is
desirable to remove imbalances in the shaft 302 and, to
that end, a balancing device 303 or a balancing device
304 may be added.
Balancing device 303 is connected so that it
rotates with the shaft 302 and the movable weights in
the form of balls 305, 307, 308 move about axis 306 of
shaft 302 in races which are positioned concentrically
and outwardly in a plane transverse to the direction of
axis 306 and, in balancing device 304, the weights in
the form of balls 310, 311, 312 rotate in races which
are longitudinally spaced and coaxial to shaft 32.
The balls 305, 307, 308 are of different
diameters and this applies likewise to the diameter of
balls 310, 311, 312. Either configuration may be
useful depending upon the geometrical considerations
present in the system which is being used which
includes shaft 302 and bearing 300.
Reference is now made to Figure 15A which
illustrates the clothes containing cylinder or "spin
basket" 400 of an ordinary washing machine rotatable
about the axis of rotation 406. Two balancing devices
402, 403 are connected to the basket 400 to remove any
imbalance upon operation although one, of course, may
be sufficient to remove imbalances. The balaacing
devices 402, 403 may again take two different forms.
Referring initially to Figure 158, the
balancing device 402 may take the form of a plurality
~ WO 95/32372 21$9Gry p PCTICA95100299
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of races 404, 405 which extend circumferentially about
axis 406 and are coaxial with axis 406. Movable
weights in the form of balls 407, 408 are mounted in
the races 404, 405 and serve to remove imbalances when
the basket 400 is rotated.
Alternatively, the balancing device 402 may
have races 409, 410 machined in a plane transverse to
axis 406. The balls 411, 412 are movable in their
respective races 409, 410 and, again, remove imbalances
when the basket 400 rotates about axis 406.
Yet a further embodiment of the invention is
illustrated in Figure 16 in which the rear end of a
vehicle 500 is diagrammatically shown. A.gear box or
differential 501 has two axles 502, 503 extending
outwardly from the gearbox 501 and connect to wheels
504, 505 which, of course, rotate with axles 502, 503
when the vehicle is under operation.
An imbalance may arise in the system. For
example, the tires 504, 505 may become out of balance
for various reasons including the fact that flats form
on the tires. This is particularly true in formula
race cars where the speeds of the cars vary greatly
throughout a circuit and the tires are subjected to
highly variable forces.
To correct the imbalance, balancing devices
506, 507, 508, 509 may be added to axles 502, 503,
respectively, although only one per axle may be
required. These would function in the same way as has
been discussed as the axles 502, 503 rotate both
axially and about gearbox 501 as is illustrated. In
the event the rotation about gearbox 501 is not severe,
it may be convenient to mount the balancing devices
WO 95/32372 Q1Qt3A C7Q PCT/CA95/00299
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508, 509 on the wheels 504, 505 rather than on the
axles 502, 503 as is shown in Figure 16.
Reference is now made to Figure 17 which
illustrates a crankshaft 600 having a crankpin 605 to
which is attached piston rod 601 which is connected to
piston 602. Piston 602 may be used, for example, in a
compressor. Two balancing devices 603, 604 are
connected to crankshaft 600 as illustrated. The
operation of each is similar to the operations
described and they serve to continuously remove
imbalances in the system as previously set forth.
Reference is now made to Figure 18 wherein
six circumferential and concentric races are
illustrated in the balancing device 700. In the three
(3) outer races 701, 702, 703, the weights 704 are of
identical diameters. In the inner races 710, 711, 712,
the balls 713 in race 710 are of identical size while
balls 714 in race 711 are of identical size and balls
715 in race 712 are of identical size, the sizes of the
balls 713, 714 and 715 decreasing as the axis 716 is
approached.
Reference is now made to Figures 19A and 19B
wherein a further embodiment of the invention is
illustrated which utilizes a circumferential I-beam and
movable weight combination generally illustrated at
800. The I-beam 801 is mounted around the
circumference of member 802 which rotates about axis
803 by welding or by attachment, for example, and a
plurality of movable weights 804 are mounted on the I-
beam 801 so as to be movable relative thereto. This
embodiment of the invention has the advantage that it
is inexpensive to manufacture and may be convenient in
some applications such as where friction between the
WO 95/32372 n PCTlCA95/00299
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weights 804 and the I-beam 801 is not a large problem
such as where the apparatus 800 is submerged in a
liquid.
Reference is now made to Figure 20 which
illustrates an apparatus generally shown at 900 having
a plurality of races 901 with movable weights 902
therein mounted about a member at increasing distances
from the axis of rotation 903. While the weights 902
are shown as increasing in size as the distance of the
weights 902 from the axis 903 increases, it will be
understood that the sizes may remain constant or,
indeed, the size may decrease as distance from the axis
903 increases.
Yet a further embodiment of the invention is
illustrated in Figure 21. In this embodiment, a
plurality of weights or balls generally illustrated at
1000 is illustrated in a race 1001 in which,
ordinarily, the weights 1000 are free to move. A
circular disc 1002 is mounted about the periphery of
the balancing apparatus generally illustrated at 1003
and this disc 1002 is axially movable as indicated by
the arrows by the influence of a two way solenoid 1004.
The disc 1002 is operably connected to plate 1010 by
pins 1011 located about its periphery.
The solenoid 1004 is connected to a
tachometer (not shown) which measures the RPM count of
the balancing apparatus 1003. When the tachometer
reading reaches a certain and predetermined value, it
initiates movement of the plate 1010 by activating
solenoid 1004. When the solenoid 1004 moves leftwardly
as viewed in Figure 1, it will lock the weights or
balls 1000 in position. Thereafter, when the
tachometer reaches a second value, it will move the
WO 95/32372 2189678 PCT/CA95/00299
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yp e
solenoid 1004 rightwardly which will move plate 1002
away from and release the balls or weights 1000. Such
a configuration can be useful when it is desired to
remove an imbalance over a certain speed range and,
thereafter, to lock the balls 1000 in place after they
assume a final balancing position to remove any
imbalance which exists when the weights 1000 have been
released.
Reference is now made to Figure 22. In this
embodiment, the weights or balls 1100 are held or
"locked" in position by the force exerted between the
balls 1100 and a material 1101, conveniently rubber,
which is positioned within the groove 1103. One side
of the rubber ball retaining material 1101 is mounted
in a movable half-groove collar 1110. Collar 1110 has
a plurality of spring mounted pins 1111 which tend to
bias the collar 1110 into contact with control balls
1112 mounted intermittently about the circumference of
the balancing apparatus 1113. Each of the control
balls 1112 are biased to move inwardly by springs 1114.
In operation, when the balancing apparatus
1113 commences rotation, the balancing weights 1100 are
securely held in position by the collar 1110 and the
face plate 1120 until a predetermined rotation speed is
reached. Thereafter, centrifugal force tending to move
control balls 1112 outwardly against the force of
springs 1114, will allow the balls 1112 to move
outwardly relative to the axis of rotation 1121 until
the collars 1110 are not restrained by being in contact
with balls 1112. Collars 1110 will move towards each
other thereby releasing the balancing balls 1100 and
allowing them to move freely into a position wherein
any imbalance is substantially reduced or removed.
When the apparatus subsequently is lowered in rotation
WO 95/32372 } PCT/CA95100299
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speed, balls 1112 will be forced inwardly by springs
1114, the collars 1110 will move outwardly to retain
the balancing balls 1100 which will subsequently be
held in position until the predetermined angular
rotation speed is again substantially reached.
Reference is now made to Figure 23 in which
the balancing apparatus is generally illustrated at
1200 which rotates about axis 1201. Apparatus 1200 has
three grooves or races 1202, 1203, 1204. A plurality
of balancing balls 1210 are freely movable in groove
1202 and a second set of balancing balls 1211 are
locked in the position shown in groove 1203 by a
friction pad 1212 mounted in groove 1203 and an axially
movable collar 1213. Likewise, a plurality of control
balls 1214 are intermittently positioned around the
circumference of groove 1204 between the outer face
1220 of balancing device 1200 and the inside wedge
shaped surface of movable collar 1213. A flat spring
1221 connected to bolt 1222 maintains force on the
collar 1213 tending to bias the collar 1213 leftwardly
as viewed in Figure 23.
In operation, as the balancing device 1200 is
initially rotated, balancing balls 1210 are free to
move within groove 1202 and will reach a position
tending to remove any imbalance then existing. At a
predetermined angular velocity, however, the control
balls 1214 will tend to move outwardly with a force
sufficient to move collar 1213 rightwardly against the
force of flat spring 1221. As collar 1213 moves
rightwardly, balls 1211 are released and, again, will
quickly assume a configuration that tends to remove any
imbalance in the apparatus. When the rotational speed
of the balancing device 1200 is decreased, the collar
1213 will trap the balls 1211 in position which will be
WO 95/32372 21~~~ ry O PC'TICA95100299
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maintained until the rotational speed of the apparatus
is again sufficient to move the control balls 1214
outwardly against the wedge shaped surface 1223 of
movable collar 1213.
It is further contemplated in the embodiment
of Figure 23 that if it is desired to maintain the
balancing balls 1211 in race 1203 in the locked
position under all rotational circumstances, bolt 1224
is simply tightened which will remove all axial
movement in collar 1213 until the operator desires
otherwise and manually loosens bolt 1224.
Two representative configurations for the
races are illustrated in Figure 24. The first race
1312 is round as illustrated. A plurality of weights
1313 are positioned in the first race 1312. Fluid 1314
is also placed within the first race 1312.
The second race 1320 is of a square
configuration with balls 1321 positioned within the
race 1320. Fluid 1322 is also placed within the second
race 1320.
other factors being equal, the shear forces
exerted on the balls 1313 will be higher than the shear
forces exerted on the balls 1321 by the fluid 1322 in
race 1320 because of the closer average distance
between the balls and the inner wall of the race.
Thus, the movement of the balls 1321, 1313 could be
staggered, for example, by placing fluid having the
same viscosity in two races having different
configurations. This would be intended to have the
same affect as having fluids of different viscosities
in races having the same configuration.
WO 95/32372 PCT1CA95100299
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It will be understood that although the balls
or weights in the races are shown to be of different
sizes and weights, the densities of the materials may
differ such that, for example, the balls or weights in
one race may be the same size as the balls or weights
in a second race although the weights are different
because of the two different materials. Likewise, the
weights may be of different sizes in the respective
races but have the same weights, again because of the
densities of the materials used.
Likewise, it is envisioned that a member
having at least three pathways with the same width,
with all of the balls or weights being of equal size,
could be satisfactorily used in certain circumstances.
The pathways would conveniently be concentric and
taking the same form, for example, as the embodiment
illustrated in Figure 18 but with the three inner races
or pathways removed.
While it is presently anticipated that the
counterbalancing apparatus according to the invention
be made from a metallic material, it is also
contemplated that other materials may well be
appropriate such as composite material structures and
plastics or the like, depending on the operating
conditions under which the counterbalancing apparatus
is intended to function.
While specific embodiments of the invention
have been described, such embodiments should be
considered as illustrative of the invention only and
not as limiting its scope as defined in accordance with
the accompanying claims.
